Composite Aggregate Architecture

This application claims priority to and is a continuation of U.S. application Ser. No. 18/419,276, filed on Jan. 22, 2024, now allowed, titled “COMPOSITE AGGREGATE ARCHITECTURE,” which claims priority to and is a continuation of U.S. Pat. No. 11,880,578, filed on Nov. 29, 2021, titled “COMPOSITE AGGREGATE ARCHITECTURE,” which claims priority to and is a continuation of U.S. Pat. No. 11,188,246, filed on Nov. 21, 2019, titled “COMPOSITE AGGREGATE ARCHITECTURE,” which claims priority to and is a continuation of U.S. Pat. No. 10,521,143, filed on Mar. 23, 2017 and titled “COMPOSITE AGGREGATE ARCHITECTURE,” which are incorporated herein by reference.

Many storage systems may provide clients with access to data stored within a plurality of storage devices. For example, a storage controller may store client data within a set of storage devices that are locally accessible (e.g., locally attached to the storage controller) or remotely accessible (e.g., accessible over a network). A storage aggregate of storage may be generated from the set of storage devices (e.g., the storage aggregate may be stored across multiple storage devices). The storage aggregate may be exported from a storage file system to a client. The storage aggregate may appear as a single storage container to the client, such as a volume or logical unit number (lun). In this way, the aggregate abstracts away the details, from the client, of how the aggregate is physically stored amongst the set of storage devices.

Some storage systems may store data within a multi-tiered storage arrangement. For example, the storage controller may store data within a hard disk drive tier and a solid state storage tier. The hard disk drive tier may be used as a capacity tier to store client data and for processing input/output operations. The solid state storage tier may be used as a cache for accelerating the processing of storage operations. Unfortunately, different classes of storage devices and media have different characteristics and behaviors (e.g., latency, size, garbage collection, efficiency of random storage operations, efficiency of sequential storage operations, I/O access sizes such as a 4 kilobyte I/O access size, etc.). Thus, a storage file system is unable to natively create an aggregate from multiple heterogeneous storage devices and media.

Some examples of the claimed subject matter are now described with reference to the drawings, where like reference numerals are generally used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of the claimed subject matter. It may be evident, however, that the claimed subject matter may be practiced without these specific details. Nothing in this detailed description is admitted as prior art.

One or more techniques and/or computing devices for providing a storage abstraction layer for a composite aggregate architecture are provided herein. The storage abstraction layer is provided as an indirection layer between a file system and a storage environment having a plurality of heterogeneous types of storage and storage providers (e.g., the storage abstraction layer reside below a file system layer). For example, the storage abstraction layer is configured to obtain characteristics of storage providers of the storage environment, such as of a hard disk drive tier storage provider, a solid state drive tier storage provider, an object storage provider (e.g., a third party cloud storage provider), a high availability (HA) storage provider (e.g., an HA pair of nodes), a shingled magnetic recording (SMR) storage provider, etc. Because the storage abstraction layer is below the file system layer, the storage abstraction layer is capable of perform operations that the file system layer is incapable of performing. For example, the storage abstraction layer can generate a storage aggregate from heterogeneous types of storage provided by different storage providers (e.g., an aggregate from storage of different classes of storage and media with different characteristics and behavior). The storage aggregate is exposed to the file system as though it is a single data container from homogeneous storage. The storage abstraction layer can determine where to store data (e.g., select a particular storage provider to store certain data), when and how to move data between different storage providers, how to perform garbage collection on an individual storage provider basis (e.g., freeing of storage blocks can be done separately and per storage provider/device as opposed to by the file system), and preserve storage efficiency of the file system such as deduplication, encryption, and compression.

The storage abstraction layer can span any number of nodes, and a file system can reside on number of the nodes. New storage providers and/or storage devices can be dynamically integrated with the storage abstraction layer, such as without the knowledge of or understanding by the file system. Thus, new storage providers and/or storage devices that are not natively compatible with the file system (e.g., the file system performs I/O access on 4 kilobyte chunks, whereas it is more efficient to send data to a distributed storage provider, such as a cloud provider, in larger chunks such as in megabyte or gigabyte chunks for network and processing efficiency) can still be used for the storage aggregate because the storage abstraction layer handles how and where to store data.

1 FIG. 100 100 To provide for providing a storage abstraction layer for a composite aggregate architecture,illustrates an embodiment of a clustered network environmentor a network storage environment. It may be appreciated, however, that the techniques, etc. described herein may be implemented within the clustered network environment, a non-cluster network environment, and/or a variety of other computing environments, such as a desktop computing environment. That is, the instant disclosure, including the scope of the appended claims, is not meant to be limited to the examples provided herein. It will be appreciated that where the same or similar components, elements, features, items, modules, etc. are illustrated in later figures but were previously discussed with regard to prior figures, that a similar (e.g., redundant) discussion of the same may be omitted when describing the subsequent figures (e.g., for purposes of simplicity and ease of understanding).

1 FIG. 1 FIG. 100 100 102 104 106 102 104 116 118 102 104 116 118 116 118 116 118 108 110 128 130 is a block diagram illustrating the clustered network environmentthat may implement at least some embodiments of the techniques and/or systems described herein. The clustered network environmentcomprises data storage systemsandthat are coupled over a cluster fabric, such as a computing network embodied as a private Infiniband, Fibre Channel (FC), or Ethernet network facilitating communication between the data storage systemsand(and one or more modules, component, etc. therein, such as, nodesand, for example). It will be appreciated that while two data storage systemsandand two nodesandare illustrated in, that any suitable number of such components is contemplated. In an example, nodes,comprise storage controllers (e.g., nodemay comprise a primary or local storage controller and nodemay comprise a secondary or remote storage controller) that provide client devices, such as host devices,, with access to data stored within data storage devices,. Similarly, unless specifically provided otherwise herein, the same is true for other modules, elements, features, items, etc. referenced herein and/or illustrated in the accompanying drawings. That is, a particular number of components, modules, elements, features, items, etc. disclosed herein is not meant to be interpreted in a limiting manner.

102 104 It will be further appreciated that clustered networks are not limited to any particular geographic areas and can be clustered locally and/or remotely. Thus, in one embodiment a clustered network can be distributed over a plurality of storage systems and/or nodes located in a plurality of geographic locations; while in another embodiment a clustered network can include data storage systems (e.g.,,) residing in a same geographic location (e.g., in a single onsite rack of data storage devices).

108 110 102 104 112 114 108 110 102 104 112 114 In the illustrated example, one or more host devices,which may comprise, for example, client devices, personal computers (PCs), computing devices used for storage (e.g., storage servers), and other computers or peripheral devices (e.g., printers), are coupled to the respective data storage systems,by storage network connections,. Network connection may comprise a local area network (LAN) or wide area network (WAN), for example, that utilizes Network Attached Storage (NAS) protocols, such as a Common Internet File System (CIFS) protocol or a Network File System (NFS) protocol to exchange data packets, a Storage Area Network (SAN) protocol, such as Small Computer System Interface (SCSI) or Fiber Channel Protocol (FCP), an object protocol, such as S3, etc. Illustratively, the host devices,may be general-purpose computers running applications, and may interact with the data storage systems,using a client/server model for exchange of information. That is, the host device may request data from the data storage system (e.g., data on a storage device managed by a network storage control configured to process I/O commands issued by the host device for the storage device), and the data storage system may return results of the request to the host device via one or more storage network connections,.

116 118 102 104 100 The nodes,on clustered data storage systems,can comprise network or host nodes that are interconnected as a cluster to provide data storage and management services, such as to an enterprise having remote locations, cloud storage (e.g., a storage endpoint may be stored within a data cloud), etc., for example. Such a node in the clustered network environmentcan be a device attached to the network as a connection point, redistribution point or communication endpoint, for example. A node may be capable of sending, receiving, and/or forwarding information over a network communications channel, and could comprise any device that meets any or all of these criteria. One example of a node may be a data storage and management server attached to a network, where the server can comprise a general purpose computer or a computing device particularly configured to operate as a server in a data storage and management system.

116 118 In an example, a first cluster of nodes such as the nodes,(e.g., a first set of storage controllers configured to provide access to a first storage aggregate comprising a first logical grouping of one or more storage devices) may be located on a first storage site. A second cluster of nodes, not illustrated, may be located at a second storage site (e.g., a second set of storage controllers configured to provide access to a second storage aggregate comprising a second logical grouping of one or more storage devices). The first cluster of nodes and the second cluster of nodes may be configured according to a disaster recovery configuration where a surviving cluster of nodes provides switchover access to storage devices of a disaster cluster of nodes in the event a disaster occurs at a disaster storage site comprising the disaster cluster of nodes (e.g., the first cluster of nodes provides client devices with switchover data access to storage devices of the second storage aggregate in the event a disaster occurs at the second storage site).

100 116 118 120 122 124 126 120 122 116 118 108 110 112 114 108 110 120 122 106 120 116 126 118 1 FIG. As illustrated in the clustered network environment, nodes,can comprise various functional components that coordinate to provide distributed storage architecture for the cluster. For example, the nodes can comprise network modules,and disk modules,. Network modules,can be configured to allow the nodes,(e.g., network storage controllers) to connect with host devices,over the storage network connections,, for example, allowing the host devices,to access data stored in the distributed storage system. Further, the network modules,can provide connections with one or more other components through the cluster fabric. For example, in, the network moduleof nodecan access a second data storage device by sending a request through the disk moduleof node.

124 126 128 130 116 118 116 118 106 128 130 124 126 128 130 116 118 128 130 116 118 Disk modules,can be configured to connect one or more data storage devices,, such as disks or arrays of disks, flash memory, or some other form of data storage, to the nodes,. The nodes,can be interconnected by the cluster fabric, for example, allowing respective nodes in the cluster to access data on data storage devices,connected to different nodes in the cluster. Often, disk modules,communicate with the data storage devices,according to the SAN protocol, such as SCSI or FCP, for example. Thus, as seen from an operating system on nodes,, the data storage devices,can appear as locally attached to the operating system. In this manner, different nodes,, etc. may access data blocks through the operating system, rather than expressly requesting abstract files.

100 It should be appreciated that, while the clustered network environmentillustrates an equal number of network and disk modules, other embodiments may comprise a differing number of these modules. For example, there may be a plurality of network and disk modules interconnected in a cluster that does not have a one-to-one correspondence between the network and disk modules. That is, different nodes can have a different number of network and disk modules, and the same node can have a different number of network modules than disk modules.

108 110 116 118 112 114 108 110 116 118 116 118 108 110 108 110 120 122 116 118 102 104 Further, a host device,can be networked with the nodes,in the cluster, over the storage networking connections,. As an example, respective host devices,that are networked to a cluster may request services (e.g., exchanging of information in the form of data packets) of nodes,in the cluster, and the nodes,can return results of the requested services to the host devices,. In one embodiment, the host devices,can exchange information with the network modules,residing in the nodes,(e.g., network hosts) in the data storage systems,.

128 130 132 In one embodiment, the data storage devices,comprise volumes, which is an implementation of storage of information onto disk drives or disk arrays or other storage (e.g., flash) as a file-system for data, for example. In an example, a disk array can include all traditional hard drives, all flash drives, or a combination of traditional hard drives and flash drives. Volumes can span a portion of a disk, a collection of disks, or portions of disks, for example, and typically define an overall logical arrangement of file storage on disk space in the storage system. In one embodiment a volume can comprise stored data as one or more files that reside in a hierarchical directory structure within the volume.

Volumes are typically configured in formats that may be associated with particular storage systems, and respective volume formats typically comprise features that provide functionality to the volumes, such as providing an ability for volumes to form clusters. For example, where a first storage system may utilize a first format for their volumes, a second storage system may utilize a second format for their volumes.

100 108 110 102 104 132 108 120 116 102 116 128 124 128 132 132 102 112 110 122 118 104 102 118 130 126 132 130 In the clustered network environment, the host devices,can utilize the data storage systems,to store and retrieve data from the volumes. In this embodiment, for example, the host devicecan send data packets to the network modulein the nodewithin data storage system. The nodecan forward the data to the data storage deviceusing the disk module, where the data storage devicecomprises volumeA. In this way, in this example, the host device can access the volumeA, to store and/or retrieve data, using the data storage systemconnected by the storage network connection. Further, in this embodiment, the host devicecan exchange data with the network modulein the nodewithin the data storage system(e.g., which may be remote from the data storage system). The nodecan forward the data to the data storage deviceusing the disk module, thereby accessing volumeB associated with the data storage device.

100 128 116 130 118 128 130 128 130 116 118 100 It may be appreciated that providing a storage abstraction layer for a composite aggregate architecture may be implemented within the clustered network environment. In an example, a storage abstraction layer may generate and maintain a first storage bin to manage the data storage deviceof the node(e.g., a first storage provider) and a second storage bin to manage the data storage deviceof the node(e.g., a second storage provider). The storage abstraction layer may be an indirection layer underneath a storage file system layer. The storage abstraction layer generates and exposes a single storage aggregate, derived from the data storage deviceand the data storage device, to a file system notwithstanding the data storage devices,being heterogeneous types of storage. It may be appreciated that providing a storage abstraction layer for a composite aggregate architecture may be implemented for and/or between any type of computing environment, and may be transferrable between physical devices (e.g., node, node, a desktop computer, a tablet, a laptop, a wearable device, a mobile device, a storage device, a server, etc.) and/or a cloud computing environment (e.g., remote to the clustered network environment).

2 FIG. 1 FIG. 1 FIG. 1 FIG. 1 FIG. 200 102 104 200 202 116 118 234 128 130 202 205 108 110 202 216 234 202 205 234 is an illustrative example of a data storage system(e.g.,,in), providing further detail of an embodiment of components that may implement one or more of the techniques and/or systems described herein. The data storage systemcomprises a node(e.g., nodes,in), and a data storage device(e.g., data storage devices,in). The nodemay be a general purpose computer, for example, or some other computing device particularly configured to operate as a storage server. A host device(e.g.,,in) can be connected to the nodeover a network, for example, to provide access to files and/or other data stored on the data storage device. In an example, the nodecomprises a storage controller that provides client devices, such as the host device, with access to data stored within data storage device.

234 224 226 228 218 220 222 224 226 228 The data storage devicecan comprise mass storage devices, such as disks,,of a disk array,,. It will be appreciated that the techniques and systems, described herein, are not limited by the example embodiment. For example, disks,,may comprise any type of mass storage devices, including but not limited to magnetic disk drives, flash memory, and any other similar media adapted to store information, including, for example, data (D) and/or parity (P) information.

202 204 206 210 212 214 242 200 208 206 202 The nodecomprises one or more processors, a memory, a network adapter, a cluster access adapter, and a storage adapterinterconnected by a system bus. The data storage systemalso includes an operating systeminstalled in the memoryof the nodethat can, for example, implement a Redundant Array of Independent (or Inexpensive) Disks (RAID) optimization technique to optimize a reconstruction process of data of a failed disk in an array.

208 215 106 202 234 208 200 208 1 FIG. The operating systemcan also manage communications for the data storage system, and communications between other data storage systems that may be in a clustered network, such as attached to a cluster fabric(e.g.,in). Thus, the node, such as a network storage controller, can respond to host device requests to manage data on the data storage device(e.g., or additional clustered devices) in accordance with these host device requests. The operating systemcan often establish one or more file systems on the data storage system, where a file system can include software code and data structures that implement a persistent hierarchical namespace of files and directories, for example. As an example, when a new data storage device (not shown) is added to a clustered network system, the operating systemis informed where, in an existing directory tree, new files associated with the new data storage device are to be stored. This is often referred to as “mounting” a file system.

200 206 204 210 212 214 204 210 212 214 208 206 In the example data storage system, memorycan include storage locations that are addressable by the processorsand adapters,,for storing related software application code and data structures. The processorsand adapters,,may, for example, include processing elements and/or logic circuitry configured to execute the software code and manipulate the data structures. The operating system, portions of which are typically resident in the memoryand executed by the processing elements, functionally organizes the storage system by, among other things, invoking storage operations in support of a file service implemented by the storage system. It will be apparent to those skilled in the art that other processing and memory mechanisms, including various computer readable media, may be used for storing and/or executing application instructions pertaining to the techniques described herein. For example, the operating system can also utilize one or more control files (not shown) to aid in the provisioning of virtual machines.

210 200 205 216 205 108 110 205 200 1 FIG. The network adapterincludes the mechanical, electrical and signaling circuitry needed to connect the data storage systemto a host deviceover a network, which may comprise, among other things, a point-to-point connection or a shared medium, such as a local area network. The host device(e.g.,,of) may be a general-purpose computer configured to execute applications. As described above, the host devicemay interact with the data storage systemin accordance with a client/host model of information delivery.

214 208 202 205 200 224 226 228 214 214 204 214 242 210 212 205 216 215 The storage adaptercooperates with the operating systemexecuting on the nodeto access information requested by the host device(e.g., access data on a storage device managed by a network storage controller). The information may be stored on any type of attached array of writeable media such as magnetic disk drives, flash memory, and/or any other similar media adapted to store information. In the example data storage system, the information can be stored in data blocks on the disks,,. The storage adaptercan include input/output (I/O) interface circuitry that couples to the disks over an I/O interconnect arrangement, such as a storage area network (SAN) protocol (e.g., Small Computer System Interface (SCSI), ISCSI, hyperSCSI, Fiber Channel Protocol (FCP)). The information is retrieved by the storage adapterand, if necessary, processed by the one or more processors(or the storage adapteritself) prior to being forwarded over the system busto the network adapter(and/or the cluster access adapterif sending to another node in the cluster) where the information is formatted into a data packet and returned to the host deviceover the network(and/or returned to another node attached to the cluster over the cluster fabric).

218 220 222 230 232 224 226 228 224 226 228 230 218 220 224 226 In one embodiment, storage of information on disk arrays,,can be implemented as one or more storage volumes,that are comprised of a cluster of disks,,defining an overall logical arrangement of disk space. The disks,,that comprise one or more volumes are typically organized as one or more groups of RAIDs. As an example, volumecomprises an aggregate of disk arraysand, which comprise the cluster of disksand.

224 226 228 208 In one embodiment, to facilitate access to disks,,, the operating systemmay implement a file system (e.g., write anywhere file system) that logically organizes the information as a hierarchical structure of directories and files on the disks. In this embodiment, respective files may be implemented as a set of disk blocks configured to store information, whereas directories may be implemented as specially formatted files in which information about other files and directories are stored.

200 Whatever the underlying physical configuration within this data storage system, data can be stored as files within physical and/or virtual volumes, which can be associated with respective volume identifiers, such as file system identifiers (FSIDs), which can be 32-bits in length in one example.

234 A physical volume corresponds to at least a portion of physical storage devices whose address, addressable space, location, etc. doesn't change, such as at least some of one or more data storage devices(e.g., a Redundant Array of Independent (or Inexpensive) Disks (RAID system)). Typically the location of the physical volume doesn't change in that the (range of) address(es) used to access it generally remains constant.

224 226 228 A virtual volume, in contrast, is stored over an aggregate of disparate portions of different physical storage devices. The virtual volume may be a collection of different available portions of different physical storage device locations, such as some available space from each of the disks,, and/or. It will be appreciated that since a virtual volume is not “tied” to any one particular storage device, a virtual volume can be said to include a layer of abstraction or virtualization, which allows it to be resized and/or flexible in some regards.

238 236 235 240 238 Further, a virtual volume can include one or more logical unit numbers (LUNs), directories, Qtrees, and files. Among other things, these features, but more particularly LUNS, allow the disparate memory locations within which data is stored to be identified, for example, and grouped as data storage unit. As such, the LUNsmay be characterized as constituting a virtual disk or drive upon which data within the virtual volume is stored within the aggregate. For example, LUNs are often referred to as virtual drives, such that they emulate a hard drive from a general purpose computer, while they actually comprise data blocks stored in various parts of a volume.

234 238 202 230 232 214 202 238 In one embodiment, one or more data storage devicescan have one or more physical ports, wherein each physical port can be assigned a target address (e.g., SCSI target address). To represent respective volumes stored on a data storage device, a target address on the data storage device can be used to identify one or more LUNs. Thus, for example, when the nodeconnects to a volume,through the storage adapter, a connection between the nodeand the one or more LUNsunderlying the volume is created.

214 206 204 230 238 In one embodiment, respective target addresses can identify multiple LUNs, such that a target address can represent multiple volumes. The I/O interface, which can be implemented as circuitry and/or software in the storage adapteror as executable code residing in memoryand executed by the processors, for example, can connect to volumeby using one or more addresses that identify the one or more LUNs.

200 202 202 202 202 205 202 205 It may be appreciated that providing a storage abstraction layer for a composite aggregate architecture may be implemented for the data storage system. In an example, a storage abstraction layer may generate and maintain a first storage bin to manage storage of the node(e.g., a first storage provider). The storage abstraction layer may maintain other storage bins for managing storage (e.g., storage devices with different characteristics than the storage of the node) of other nodes. In this way, the storage abstraction layer generates and exposes a single storage aggregate, derived from storage of the nodeand/or storage other storage providers, to a file system. It may be appreciated that providing a storage abstraction layer for a composite aggregate architecture may be implemented for and/or between any type of computing environment, and may be transferrable between physical devices (e.g., node, host device, a desktop computer, a tablet, a laptop, a wearable device, a mobile device, a storage device, a server, etc.) and/or a cloud computing environment (e.g., remote to the nodeand/or the host device).

300 3 FIG. One embodiment of providing a storage abstraction layer for a composite aggregate architecture is illustrated by an exemplary methodof. A storage abstraction layer (e.g., a set of classes, functionality, protocol functionality, policies, network communication functionality, storage management functionality, etc. that can provide a transparent interface to various storage providers) can be utilized as an indirection layer between a file system (e.g., a storage file system) and a storage environment (e.g., storage providers accessible over one or more networks). The storage abstraction layer can abstract away the details regarding where and how data is stored amongst a plurality of different types of storage providers and storage devices. For example, the storage abstraction layer may expose a storage aggregate/pool that appears to be a single storage container to the file system. Thus, the file system merely reads and writes to that single storage container. However, the storage abstraction layer intercepts the read and write requests, and determines where and how to store and retrieve data.

302 At, the storage abstraction layer obtains characteristics of a plurality of storage providers that provide access to heterogeneous types of storage of the storage environment. The characteristics may relate to latency, storage capacity, type of storage device/media (e.g., magnetic storage, solid state/flash storage, cloud storage, high availability storage, memory or NVRAM, locally attached storage, remote storage, shingled magnetic recording storage, etc.), I/O access size, garbage collection policies, supported storage access protocols, encryption used, how data is stored (e.g., stored as blocks of data having a particular size), how data is referenced/indexed (e.g., referenced by an object ID and an offset within the object ID for particular data, referenced by a physical block number, referenced by a logical block number, referenced by a file name, referenced by an offset, etc.), etc.

In an example, the storage abstraction layer may communicate with a first node and a second node (e.g., a high availability node pairing) that provide high availability access to locally attached data storage in order to obtain characteristics of the nodes and their storage. In another example, the storage abstraction layer may communicate, over a network, to a distributed object storage provider (e.g., cloud storage provided by a third party provider) that provides object storage in order to obtain characteristics of the distributed storage provider and the object storage. In this way, a variety of storage providers may be accessed in order to obtain the characteristics. Because the storage abstraction layer can interface with multiple different types of storage providers, the file system can be hosted across any number of nodes and the storage abstraction layer can create aggregates from storage hosted by multiple different types of nodes and storage providers.

304 At, a first storage bin may be generated, by the storage abstraction layer, to manage first storage of a first storage provider. The first storage bin may be configured based upon first characteristics of the first storage provider. For example, the first storage bin may be configured to access the first storage provider (e.g., a solid state storage provider) using a particular protocol and I/O access size used by the first storage provider. The first storage bin may be configured to use certain types of compression, encryption, garbage collection policies, data formats, and/or data reference formats (e.g., refer to data by physical block numbers, logical block numbers, file names, object identifiers, offsets, etc.) associated with the first storage provider.

306 At, a second storage bin may be generated, by the storage abstraction layer, to manage second storage of a second storage provider. The second storage bin may be configured based upon second characteristics of the second storage provider. For example, the second storage bin may be configured to access the second storage provider (e.g., a cloud storage provider) using a protocol and/or I/O access size used by the second storage provider. The second storage bin may be configured to use certain types of compression, encryption, garbage collection policies, data formats, and/or data reference formats (e.g., refer to data by physical block numbers, logical block numbers, file names, object identifiers, offsets, etc.) associated with the second storage provider.

It may be appreciated that the storage abstraction layer may generate any number of storage bins for any number of storage providers for which the storage abstraction layer is to abstract away the details of physically storing data from the file system. The storage providers may store data in different manners and provide access to data in different ways. For example, the first storage provider may support a first I/O size such as a 4 kilobyte I/O size for reading/writing data. In contrast, the second storage provider may support a second I/O size such as an unconstrained range up to 1 gigabyte. For example, it may be more efficient to send data to the cloud storage provider in larger chunks such as chunks in a megabyte or gigabyte range, which may more efficiently utilize network bandwidth and processing resources. Even though the file system may merely support the first I/O size, the storage abstraction layer can use the second storage bin as an intermediary interface to handle the details of how data will be sent to, stored within, and accessed from the cloud storage provider using the second I/O size.

308 310 At, a storage aggregate is generated, by the storage abstraction layer, from the first storage having a first storage type (e.g., solid state drive storage provided by the first storage provider), the second storage having a second storage type different than the first storage type (e.g., object storage provided by the cloud storage provider), and/or other storage from other storage providers. The storage abstraction layer will use individual storage bins to manage where and how to store and access data within each storage of each storage provider. At, the storage aggregate is exposed to the file system as a single storage container. For example, the storage abstraction layer may expose the storage aggregate as a single volume, a single LUN, or other data container while abstracting away the notion that the storage aggregate is actually composed of portions of storage from multiple storage provider. In an example, the storage abstraction layer may expose merely a subset of characteristics of the storage providers to the file system (e.g., a type of storage may be exposed, but not other characteristics like how old/stale data blocks are freed, overwritten, etc.).

The storage abstraction layer is utilized to selectively store a plurality of data from the file system through storage bins to corresponding storage of the plurality of storage providers based upon characteristics of data and characteristics of storage providers. A characteristic may corresponding to a sequential access characteristic, a random access characteristic, a user data characteristic, a metadata characteristic (e.g., a replication policy, a backup policy, a LUN configuration, an identification of a partner node, and/or other metadata used by the file system or nodes for operation), a frequently accessed characteristic (e.g., hot data having an access frequency/pattern above a threshold), an infrequently accessed characteristic (e.g., cold data having an access frequency/pattern below the threshold), etc. The storage abstraction layer is configured to determine which type of storage and storage provider is better suited to store certain types of data (e.g., a cloud storage provider may be more cost effective to store infrequently accessed user data, whereas a shingled magnetic recording storage provider may be better for frequently accessed metadata and a high availability storage provider with additional redundancy may be better for mission critical data).

In an example, a request may be received from the file system to store first data within the storage aggregate. Because the storage aggregate is exposed as a single storage container, the request does not specify which storage provider and/or type of storage the first data is to be stored. Accordingly, the storage abstraction layer may selectively store the first data, through the first storage bin, into a first storage location of the first storage and not into the second storage based upon a data characteristic of the first data corresponding to a characteristic of the first storage provider (e.g., the first storage may be more efficient for storing sequentially accessed data than the second storage). At some point in time, the storage abstraction layer may determine that the first data should be moved from the first storage location within the first storage to a second storage location within the second storage of the second storage provider. Accordingly, the storage abstraction layer moves the first data from the first storage to the second storage at the second storage location, which may be performed transparent to the file system since the storage abstraction layer abstracts away the physical storage details of data of the storage aggregate from the file system.

An overwrite request, to overwrite the first data with new data, may be received by the storage abstraction layer from the file system. In an example where the file system is a write anywhere file system, the new data may not be written to a current location of the first data (e.g., the second storage location of the second storage) but is written to a different location that is free/available. Thus, at some point, the first data at that current location will need to be garbage collected so that the current location is freed and available to store other data since the first data at the second storage location has become stale once the new data is written to the different location. The storage abstraction layer may store the new data of the overwrite request into a third storage location as new first data. The third storage location may be within the first storage where the first data was previously located before being moved/migrated, or within the second storage where the first data is currently located at the second storage location, or within any other storage of any other storage provider. The second storage bin may be used to mark the first data at the second storage location for garbage collection so that the second storage location can be freed and available for data storage since the new first data at the third storage location is a most up-to-date version. Garbage collection may be facilitated on a storage provider by storage provider basis in a manner that is transparent to the file system (e.g., different garbage collection policies may be implemented for different storage providers).

In an example, the storage abstraction layer may track various metrics regarding data, such as a first frequency of access to data (A) within the first storage, a second frequency of access to data (B) within the second storage, etc. Responsive to the storage abstraction layer determining that the first frequency of access is below a threshold set by the first storage bin for the first storage, the data (A) may be accumulated from the first storage into a log of the first storage bin. Responsive to the storage abstraction layer determining that the second frequency of access is below a threshold set by the second storage bin for the second storage, the data (B) may be accumulated from the second storage into a second log of the second storage bin.

The storage abstraction layer may determine that a threshold amount of data has been accumulated into the log of the first storage bin for the first storage (e.g., a threshold amount of cold data may be collected from the solid state drive storage of the solid state drive storage provider into the first storage bin). Accordingly, the storage abstraction layer may generate a storage object, corresponding to a data format of the second storage (e.g., the cloud storage provider may store data within objects), comprising the accumulated data from the log such as the data (A). In this way, the storage object may comprise data of various files, directories, applications, etc. The storage abstraction layer sends the storage object, through the second storage bin, to the second storage provider for storage within the second storage. It may be appreciated that accumulated data from any type of storage provider may be used to generate any type of data object/container that is compatible with a destination for the accumulated data (e.g., a block based data format, a file, a LUN, a storage object, a database file, etc.). The storage abstraction layer may populate an object metafile with one or more entries indication what data is stored within the storage object (e.g., data references used by the file system to reference the data such as virtual block numbers), and object identifier of the storage object, and offsets of such data.

The storage abstraction layer may receive an access request for the data (A) from the file system (e.g., the file system may be unaware of the location of the data (A) as being within the storage object now stored at the second storage of the second storage provider). In an example, the access request comprises a physical volume block number or any other identifier used by the file system to reference the data (A) within the storage aggregate. The storage abstraction layer may query the object metafile using the physical volume block number to identify an object identifier of the storage object and an offset of the data (A) within the storage object. The object identifier and the offset may be used to provide access through the second storage bin to the data (A) within the storage object stored within the second storage by the second storage provider. In this way, the file system may access the data (A) notwithstanding the data (A) being comprised within the storage object, along with other data that may be unrelated, that is now stored within the second storage.

The storage abstraction layer may track reference counts of references to data stored within the storage of the storage providers (e.g., the storage abstraction layer may provide its own garbage collection for individual storage of each storage provider as opposed to adhering to what is tracked by the file system for the storage aggregate). For example, the first storage bin may be used to track reference counts of references to data within the first storage. The reference counts may be used to free data, with reference counts of zero, from the first storage because such data may be stale/unused due to new data being written elsewhere by a write anywhere file system that does not overwrite current locations of data with new data but writes the new data to open/free storage locations.

The storage abstraction layer may be configured to preserve storage efficiency of the file system. In an example, the storage abstraction layer may receive compressed data from the file system. The storage abstraction layer may store the compressed data, in a compressed state, within the first storage. Alternatively, uncompressed data that is to be compressed may be received from the file system or retrieved from a storage provider. Accordingly, the storage abstraction layer may perform compression upon the uncompressed data (e.g., within a storage bin or log), and then send the compressed data to a particular storage provider.

In another example, the storage abstraction layer may receive encrypted data from the file system. The storage abstraction layer may store the encrypted data, in an encrypted state, within the first storage. Alternatively, unencrypted data that is to be encrypted may be received from the file system or retrieved from a storage provider. Accordingly, the storage abstraction layer may encrypted the unencrypted data (e.g., within a storage bin or log), and then send the encrypted data to a particular storage provider.

In another example, the storage abstraction layer may preserve deduplication provided by the file system. For example, the storage abstraction layer may maintain its own reference count of references to data.

In an example, if data is to be moved between storage providers, then the data may be placed into a log and then compression, encryption, and/or other storage efficiency functionality may be performed upon the data within the log in order to preserve such functionality.

4 FIG. 400 404 402 402 406 404 428 406 404 illustrates an example of a systemhaving a composite storage architecture. A file system may operate at a storage file system layer. Clients may access the file system through a storage file system access layer. For example, a client may send read commands, write commands, create commands, and/or other commands to the file system through the storage file system access layer. A storage abstraction layeris provided as an indirection/intermediate layer between the file system, such as the storage file system layer, and a storage environment. The storage abstraction layeris underneath the storage file system layer.

406 428 406 408 418 408 418 418 The storage abstraction layermay obtain characteristics of storage providers within the storage environment. Based upon those characteristics, the storage abstraction layercreates storage bins for managing storage of the storage providers. Each storage bin is tailored to a particular storage provider because types of storage provided by each storage provider may have different characteristics (e.g., certain storage may perform better for random access or sequential access; certain storage may provide better redundancy; certain storage providers may provide more security; certain storage providers may provide higher availability to data; etc.). For example, a solid state drive storage binmay be generated for a solid state drive storage provider. The solid state drive storage binmay determine where and how to store data within solid state drive storage of the solid state drive storage provider, set what protocols to use, set what garbage collection technique to use, set thresholds for determining cold/hot data for the solid state drive storage provider, set what compression to use, set redundancy polices, set security policies, set what I/O access size to use, set what data format to use, determine how to reference/identify particular data, etc.

410 420 410 420 420 A hard disk drive storage binmay be generated for a hard disk drive storage provider. The hard disk drive storage binmay determine where and how to store data within hard disk drive storage of the hard disk drive storage provider, set what protocols to use, set what garbage collection technique to use, set thresholds for determining cold/hot data for the hard disk drive storage provider, set what compression to use, set redundancy polices, set security policies, set what I/O access size to use, set what data format to use, determine how to reference/identify particular data, etc.

412 422 412 422 422 An object storage binmay be generated for an object storage provider(e.g., a cloud storage provider that stores data within objects). The object storage binmay determine where and how to store data within object storage of the object storage provider, set what protocols to use, set what garbage collection technique to use, set thresholds for determining cold/hot data for the object storage provider, set what compression to use, set redundancy polices, set security policies, set what I/O access size to use, set what data format to use, determine how to reference/identify particular data, etc.

414 424 414 424 424 A shingled magnetic recording storage binmay be generated for a shingled magnetic recording storage provider. The shingled magnetic recording storage binmay determine where and how to store data within storage of the shingled magnetic recording storage provider, set what protocols to use, set what garbage collection technique to use, set thresholds for determining cold/hot data for the shingled magnetic recording storage provider, set what compression to use, set redundancy polices, set security policies, set what I/O access size to use, set what data format to use, determine how to reference/identify particular data, etc.

416 426 416 426 426 A high availability storage binmay be generated for a high availability storage provider(e.g., two nodes configured according to a high availability configuration). The high availability storage binmay determine where and how to store data within storage of the high availability storage provider, set what protocols to use, set what garbage collection technique to use, set thresholds for determining cold/hot data for the high availability storage provider, set what compression to use, set redundancy polices, set security policies, set what I/O access size to use, set what data format to use, determine how to reference/identify particular data, etc.

406 406 404 406 406 In this way, the storage abstraction layercan use the storage bins to individually manage different types of storage provided by the various storage providers. The storage abstraction layercan generate a storage aggregate comprised of portions of storage from the various storage providers notwithstanding the storage providers hosting different types of storage, using different data formats, referencing data in different manners (e.g., physical block number, file name, offset, virtual block number, etc.) using different storage protocols, using different I/O access sizes, etc. The storage aggregate can be exposed up to the file system of the storage file system layeras a single storage container. In this way, the storage abstraction layerabstracts away the details of physically sending, storing, retrieving, and managing data across the storage providers (e.g., the file system may merely issue a write command to the storage aggregate, and the storage abstraction layermay select a particular storage bin to use for selectively storing data of the write command to a particular storage provider).

5 5 FIGS.A-E 5 FIG.A 500 512 512 506 512 526 528 530 illustrate examples of a systemfor providing a storage abstraction layerfor a composite aggregate architecture. The storage abstraction layermay be provided as an indirection layer between a file systemand a storage environment, as illustrated by. The storage environment may be defined as storage providers accessible to the storage abstraction layer, such as a solid state drive storage provider, a hard disk drive storage provider, an object storage provider(e.g., a cloud storage provider hosted by a third party), and/or other local or remote storage providers.

512 The storage abstraction layermay obtain characteristics of the storage providers, such as I/O access sizes, latencies, communication protocols, indications as to whether storage is more suitable for certain types of access (e.g., random access, sequential access, frequent access, infrequent access, etc.), how data is addressed/referenced, availability (e.g., whether failover operation is provided), redundancy, backup, garbage collection, etc.

512 518 520 522 512 514 506 The storage abstraction layermay use the characteristics to generate storage bins (e.g., configured with functionality, methods, policies, classes, etc.) used to manage storage of the storage providers, such as a solid state drive storage bin, a hard disk drive storage bin, an object storage bin, etc. A storage bin may be configured to determine whether characteristics of data match characteristics of a corresponding storage provider, and thus are eligible to be stored within storage of the corresponding storage provider, otherwise, should be stored within storage of a different storage provider. The storage bin may be configured to determine where and how to store data within the storage of the corresponding storage provider. The storage bin may be configured with redundancy policy information, backup policy information, replication policy information, compression information, encryption information, deduplication information, garbage collection information, access metrics used to identify hot and cold data, what type of data is to be stored within the storage of the corresponding storage provider (e.g., user data, metadata, frequently accessed data, infrequently accessed data, sequential data, random data, encrypted data, compressed data, redundant or backup data, etc.), and/or other functionality and policies to implement for the storage of the corresponding storage provider. In this way, the storage abstraction layercomprises storage efficiency preservation functionality, such as to preserve encryption, compression, deduplication, etc. of the file system.

512 510 526 528 530 510 506 512 The storage abstraction layermay construct a storage aggregatefrom solid state drive storage of the solid state drive storage provider, hard disk drive storage of the hard disk drive storage provider, object storage of the object storage provider, and/or other types of storage of other storage providers (e.g., shingled magnetic record storage, NVRAM, high availability storage providing by a high availability node pair, locally attached storage, remotely attached storage, storage accessing through a NAS protocol, storage accessing through a SAN protocol, etc.). In this way, the storage aggregateis composed from heterogeneous types of storage, and is exposed to the file systemas a single data container where the storage abstraction layerabstractions away the particulars of how and where data is stored and managed.

506 502 510 506 506 510 502 510 502 510 506 The file systemmay provide a clientwith access to the storage aggregate. Because the file systemviews the storage aggregate as a single data container, the file systemmay expose the storage aggregateor a portion thereof to the clientas a single data container (e.g., a single volume, a single LUN, etc.). In an example, a first portion of the storage aggregatemay be exposed to the client, and a second portion of the storage aggregatemay be exposed to a different client, and thus the file systemprovides a second level of indirection to the clients.

506 504 502 524 510 504 502 510 506 502 506 508 524 510 512 508 524 524 512 524 526 518 524 526 In an example, the file systemreceives a write requestfrom the clientto write data (A)to the storage aggregate(e.g., a write requestdirected by the clientto a volume or LUN exported from the storage aggregateby the file systemto the client). The file systemmay generate a write operationto write the data (A)to the storage aggregate. The storage abstraction layermay intercept the write operationand determine data characteristics of the data (A)(e.g., is the data (A)frequently accessed data, user data, metadata, random data, sequential data, etc.). The storage abstraction layermay determine that the data characteristics of the data (A)more closely match characteristics of the solid state drive storage provider. Accordingly, the solid state drive storage binmay be used to determine where and how to storage the data (A)within solid state drive storage of the solid state drive storage provider.

512 516 The storage abstraction layer, such as individual storage bins, may maintain a log(e.g., or a log per storage bin) into which a particular type of data is accumulated so that accumulated data can be moved between storage of storage providers (e.g., cold data may be accumulated into a first log so that the cold data can be moved to a storage provider more suited for storing cold data; hot data may be accumulated into a second log so that the hot data can be moved to a storage provider more suited for storing hot data; sequentially accessed data may be accumulated into a third log so that the sequentially accessed data can be moved to a storage provider more suited for storing sequentially accessed data; randomly accessed data may be accumulated into a fourth log so that the randomly accessed data can be moved to a storage provider more suited for storing randomly accessed data; user data may be accumulated into a fifth log so that the user data can be moved to a storage provider more suited for user data; metadata may be accumulated into a sixth log so that the metadata can be moved to a storage provider more suited for metadata; etc.).

516 516 516 In an example, data (X) may be accumulated into the logbased upon a frequency of access to data (X) falling below a threshold set by a particular storage bin for a particular storage provider. For example, upon the storage bin determining that the data (X) is accessed below the threshold, the data (X) may be accumulated from storage of the storage provider into the logof that storage bin. Once a threshold amount of cold data is accumulated within the log, the accumulated cold data may be sent to a target storage provider better suited for cold data. Compression, deduplication, encryption, data formatting (e.g., storing data blocks into a storage object), and/or other storage operations may be performed upon the accumulated cold data before being sent to the target storage provider.

5 FIG.B 512 524 526 518 526 524 540 518 524 518 516 518 518 516 illustrates the storage abstraction layerdetermining that a frequency of access to the data (A)within the solid state drive storage of the solid state drive storage providerhas fallen below a threshold set by the solid state drive storage binfor the solid state drive storage provider. Accordingly, a storage location at which the data (A)is stored within the solid state drive storage may be designated(e.g., by the solid state drive storage bin) for garbage collection to later be freed so that new data can be stored within the storage location. The data (A)may be extracted from the solid state drive storage by the solid state drive storage binand accumulated into the logmaintained by the solid state drive storage bin. In this way, cold data managed by the solid state drive storage binis accumulated into the log. It may be appreciated that any type of data may be accumulated into a log for migration of such data from a particular storage provider to a different storage provider (e.g., cold data, hot data, user data, metadata, randomly accessed data, redundant data, etc.).

5 FIG.C 512 518 516 550 524 516 550 512 530 550 524 illustrates the storage abstraction layer, such as the solid state drive storage bin, determining that a threshold amount of data (e.g., cold data) has been accumulated into the log. Accordingly, a storage object(e.g., a file, a blob, a range of blocks, a data structure, a data container, an object, etc.) may be generated to comprise the data (X), the data (A), and/or other data that was accumulated into the log. Before generating the storage object, the storage abstraction layermay format the data (e.g., the data may be formatted into a type of storage object used by the object storage providerfor storing data), deduplicate the data, encrypt the data, compress the data, etc. In this way, the storage objectis a single data container into which multiple related or unrelated data may be stored (e.g., the data (X) may be metadata and the data (A)may be part of a client file).

522 550 530 550 530 522 552 550 550 The object storage binmay send the storage objectto the object storage providerthat stores the storage objectwithin object storage provided by the object storage providerand managed by the object storage bin. The object storage binmay populate an object metafile with an object identifier of the storage objectand offsets of data stored into the storage object.

5 FIG.D 502 560 506 560 502 506 524 506 510 506 562 510 512 502 506 524 illustrates the clientsubmitting an access requestto the file systemfor accessing the data (A). In one example, the clientand/or the file systemare unaware of the location of the data (A)(e.g., the file systemis merely aware of the notion of the storage aggregateas a single data container). Accordingly, the file systemsubmits an access operationto the storage aggregate, which is intercepted by the storage abstraction layer. In an example, the clientand/or the file systemmay address the data (A)by a physical volume block number or any other identifier (e.g., a file identifier, a virtual block number, etc.).

512 524 522 530 522 550 524 550 522 564 524 550 530 The storage abstraction layerdetermines that the data (A)is currently managed by the object storage binand is stored within object storage of the object storage provider. Accordingly, the object storage binmay query the object metafile using the physical volume block number to identify the object identifier of the storage objectand an offset of the data (A)within the storage object. The object identifier and the offset may be used by the object storage binto provide accessto the data (A)within the storage objectstored within the object storage by the object storage provider.

5 FIG.E 518 570 526 506 526 518 572 540 524 illustrates the solid state drive storage binperforming garbage collectionupon the solid state drive storage of the solid state drive storage provider(e.g., independent of any garbage collection and/or reference count tracking provided by the file systemand/or the solid state drive storage provider). Accordingly, the solid state drive storage binmay freethe storage location designatedfor garbage collection (e.g., the old/stale location of the data (A)).

6 FIG. 3 FIG. 4 FIG. 5 5 FIG.A-E 608 606 606 604 604 602 300 604 400 500 Still another embodiment involves a computer-readable medium comprising processor-executable instructions configured to implement one or more of the techniques presented herein. An example embodiment of a computer-readable medium or a computer-readable device that is devised in these ways is illustrated in, wherein the implementation 600 comprises a computer-readable medium, such as a compact disc-recordable (CD-R), a digital versatile disc-recordable (DVD-R), flash drive, a platter of a hard disk drive, etc., on which is encoded computer-readable data. This computer-readable data, such as binary data comprising at least one of a zero or a one, in turn comprises a processor-executable computer instructionsconfigured to operate according to one or more of the principles set forth herein. In some embodiments, the processor-executable computer instructionsare configured to perform a method, such as at least some of the exemplary methodof, for example. In some embodiments, the processor-executable computer instructionsare configured to implement a system, such as at least some of the exemplary systemofand/or at least some of the exemplary systemof, for example. Many such computer-readable media are contemplated to operate in accordance with the techniques presented herein.

It will be appreciated that processes, architectures and/or procedures described herein can be implemented in hardware, firmware and/or software. It will also be appreciated that the provisions set forth herein may apply to any type of special-purpose computer (e.g., file host, storage server and/or storage serving appliance) and/or general-purpose computer, including a standalone computer or portion thereof, embodied as or including a storage system. Moreover, the teachings herein can be configured to a variety of storage system architectures including, but not limited to, a network-attached storage environment and/or a storage area network and disk assembly directly attached to a client or host computer. Storage system should therefore be taken broadly to include such arrangements in addition to any subsystems configured to perform a storage function and associated with other equipment or systems.

In some embodiments, methods described and/or illustrated in this disclosure may be realized in whole or in part on computer-readable media. Computer readable media can include processor-executable instructions configured to implement one or more of the methods presented herein, and may include any mechanism for storing this data that can be thereafter read by a computer system. Examples of computer readable media include (hard) drives (e.g., accessible via network attached storage (NAS)), Storage Area Networks (SAN), volatile and non-volatile memory, such as read-only memory (ROM), random-access memory (RAM), electrically erasable programmable read-only memory (EEPROM) and/or flash memory, compact disk read only memory (CD-ROM) s, CD-Rs, compact disk re-writeable (CD-RW) s, DVDs, cassettes, magnetic tape, magnetic disk storage, optical or non-optical data storage devices and/or any other medium which can be used to store data.

Although the subject matter has been described in language specific to structural features or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing at least some of the claims.

Various operations of embodiments are provided herein. The order in which some or all of the operations are described should not be construed to imply that these operations are necessarily order dependent. Alternative ordering will be appreciated given the benefit of this description. Further, it will be understood that not all operations are necessarily present in each embodiment provided herein. Also, it will be understood that not all operations are necessary in some embodiments.

Furthermore, the claimed subject matter is implemented as a method, apparatus, or article of manufacture using standard application or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a computer to implement the disclosed subject matter. The term “article of manufacture” as used herein is intended to encompass a computer application accessible from any computer-readable device, carrier, or media. Of course, many modifications may be made to this configuration without departing from the scope or spirit of the claimed subject matter.

As used in this application, the terms “component”, “module,” “system”, “interface”, and the like are generally intended to refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component includes a process running on a processor, a processor, an object, an executable, a thread of execution, an application, or a computer. By way of illustration, both an application running on a controller and the controller can be a component. One or more components residing within a process or thread of execution and a component may be localized on one computer or distributed between two or more computers.

Moreover, “exemplary” is used herein to mean serving as an example, instance, illustration, etc., and not necessarily as advantageous. As used in this application, “or” is intended to mean an inclusive “or” rather than an exclusive “or”. In addition, “a” and “an” as used in this application are generally be construed to mean “one or more” unless specified otherwise or clear from context to be directed to a singular form. Also, at least one of A and B and/or the like generally means A or B and/or both A and B. Furthermore, to the extent that “includes”, “having”, “has”, “with”, or variants thereof are used, such terms are intended to be inclusive in a manner similar to the term “comprising”.

Many modifications may be made to the instant disclosure without departing from the scope or spirit of the claimed subject matter. Unless specified otherwise, “first,” “second,” or the like are not intended to imply a temporal aspect, a spatial aspect, an ordering, etc. Rather, such terms are merely used as identifiers, names, etc. for features, elements, items, etc. For example, a first set of information and a second set of information generally correspond to set of information A and set of information B or two different or two identical sets of information or the same set of information.

Also, although the disclosure has been shown and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art based upon a reading and understanding of this specification and the annexed drawings. The disclosure includes all such modifications and alterations and is limited only by the scope of the following claims. In particular regard to the various functions performed by the above described components (e.g., elements, resources, etc.), the terms used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure. In addition, while a particular feature of the disclosure may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application.